Method of coloring cellulosic materials by hot embossing



United States Patent Oflfice 2,705,682 Patented Apr. 5, 1955 METHGD OF COLORING CELLULOSIQ IVIATERIALS BY HGT EMBOSSING Karl Wille, Somerville, N. .L, assignmto American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application May 11, 1951, Serial No. 225,907

11 Claims. (Cl. 117-11) This invention relates to the treatment of coating stock or other cellulosic materials to obtain tone-on-tone etiects,

that had been previously coated with a mixture containing a white and/or colored pigment in combination with a binder such. as casein, and a wax emulsion; Such a process, however, is limited to slight dififerences in shade of the same color, whereas by the present process one may obtain two distinctly different colors.

It is an I coat paper or other cellulosic material to obtain these results may be readily prepared from low-cost available materials and the method of application of my composition is simple, as it may be applied by a continuous operation.

The present invention is used in the paper field for stationery s helf paper and decorative paper in general.

of critical factors involved, ess a very practical one.

ored pigment, a binder such and an oil-soluble color or color base. color pigment is insoluble in both water oil-soluble color or color base wax emulsion The White or and 011.

example, 110 F., the water is evaporated and mixture including pigment,

the coating binder, wax-emulsion and oil-soluble color or color base .are bound to the the casein. If this coated paper is then passed under an'embossing roll that has the point of contact and dissolve the oil-soluble pigment. This brings the n has cooled, approximately tWo a or other cellulosic material.

oil-soluble pigment to the surface as a strong contrasting color.

It will be recognized that numerous variations may be made without departing from the scope of this invention, for example, the mixture of pigment, color and wax may be applied first, followed by a second coat of the wax emulsion, or the pigment and color mixture may be applied separately. If it is desirable to improve the water resistance of the coated paper, a top water-resistant coating may be applied.

The following examples are for the purpose of illustrating the invention only, and should not be interpreted as a limitation of this disclosure.

Example I This gives a 17% casein solution.

A wax solution is prepared by heating 20 parts of borax with 700 parts of water until the borax has been dissolved. Forty-four parts of stearic acid,

parafin wax and 44 parts of beeswax are then added to r in the following examples as Mix A.

Twenty-five parts of coating clay, divided titanium dioxide, and 11 parts of Mix A are slurried in 55 parts of water. Fifty-five parts of the 17% casein solution described above are then added and thoroughly mixed, after which 20 parts of the wax solution are stirred into the mix. Th' coating is then passed a -rnesh screen two 25 parts or" finely The coating is carried out which the coated ma- F. This coatabout 270 F.

The previous example is repeated except a second coatpurposes. is prepared by using 1 described above, 30 parts of water and 1 part of formaldehyde. lt is applied after the first coat described in Example 1 has been dried, and the second coat is likewise air dried at F.

en treated with a hot embossing roll as in Example 1, the color in this example is also a blue and the coating is substantially waterproofed.

Example 3 The procedure of Example 1 is repeated except tWo coats of the materialdescribed in Example 1 are applied, paper being dried at 140 F. between coats and after the treatment. When contacted with a hot embossing roll, the blue color is pronounced in those portrons where the contact is made.

Example 4 The procedure of Example 1 is repeated except that ple 2. When this paper slurried in 55 parts of water.

two coats of the material described therein are applied. This is followed by a top coat of the casein-formaldehyde solution described in Example 2. The shade of the color is slightly greener than when no top coat is applied.

Example The procedure of Example 1 is repeated and this first coat is followed by a second application of a Wax emul sion which contained no color. The result after embossing is similar to that obtained in Example 3, but the ground color is whiter than that of Example 3.

Example 6 waterproofing casein-formaldehyde Example 2 was applied to a sample This treat A top coat of the solution described in of the paper coated according to Example 5. ment resulted in a good greenish blue shade.

Example 7 on a white background was developed.

Example 8 The waterproofing casein-formaldehyde mixture described in Example 2 was applied to a sample of the product of Example 7. A good color on an excellent white background was obtained.

tetrazotized .and coupled with was added to the coating composition before application. This was followed bythe application of a casein-formaldehyde waterproofing composition described in Examis hot embossed it gives a green design one yellow background.

Example '10 Twenty-five parts of coating clay, .25 parts of finely divided titanium dioxide, 3 parts of Mix A and 5 parts .dichlorobenzidine tetrazotized and coupled with .aceto acetorthotoluidide are Fifty-five parts of the 17% casein solution described in Example 1 are then added and thoroughly mixed, after emulsion are stirred into the mix. applied to paper stock and dried at 140 developed upon hot embossing is yellower Example 9.

This composition is F. The shade than that of Example ,11

When the composition described in Example 4 is applied to brown wrappingpaper, drie and embossed, a green color is obtained on a'brown background.

Example 12 The procedure of Example is repeated except the yellow pigment of that example is replaced with the pigment prepared from dinitranlline diazotized and coupled to beta naphthol. A two-tone effect is obtained.

Example 13 The procedure of Example 10 is repeated except the inorganic pigment red iron oxide .is used instead of the yellow pigment of that example. When the paper is dried and embossed, a gray .design on a reddish background is obtained.

Example 14 The procedure of Example 'lOLis repeated'except that the phospho molybdo tungstic lake of the dye having Color Index '6'80'is used insteadof'theyellow pigment of which 20 parts of the wax vided 'water insoluble pigment, finely pigment and a Example 10. When this paper is hot embossed it gives a blue design on a violet background.

Although casein has been employedas the water-soluble binder in all the preceding examples, it will be recognized that other binders such as gum arabic, starch, methylcellulose, etc., may be substituted for casein with similar results.

I claim:

1. A composition suitable for coating paper and other cellulosic materials which comprises an emulsion, the internal phase of said emulsion being a water-insoluble wax having a melting point above F. and below 270 F., the external phase of said emulsion being an aqueous dispersion of a finely divided water insoluble pigment and a finely divided oil-soluble color in an aqueous solution of a water-soluble binder.

2. A composition according to claim 1 in which said waxes are a mixture of beeswax and paraflin wax.

3. A composition according to claim 2 -'n w ich-said water-soluble binderis casein.

4. A composition according to claim 3 in which said insoluble pigment is titanium dioxide.

5. A sheet of'ce'llulosic material, one side of which'is coated with a binder having dispersed therein a-fine'ly .di-

divided oil-soluble color and discreet particles of water-insoluble wax, said wax particles having a melting point above 140" F. and below 270"'F.

6. A product according to claim 5 in which said wax is a mixture of beeswax and paraffin wax.

7. A product according to claim 6 in which said-insoluble pigment is titanium dioxide.

8. A product according to claim 5 which has improved water-resistance due to the presence of a second coating of a casein-formaldehyde condensate.

9. A product according to claim 5 in which said oilthe cellulosic surface and betweensaid cellulosic surface and said wax particles.

10. A method of obtaining dual color effects on cellulosic materials by hot embossing which comprises applying to one surface of said cellulosic material an emulsion, the internal phase of said emulsion being a water-insoluble waxhaving a'melting point above 140 F. and below 270 F., the external phase of said emulsion being an aqueous dispersion of a finely divided waterginsoluble finely divided oil-soluble color in an aqueous solution of a water-soluble'binder; drying said coating at a temperature substantially below the melting point ofsaid wax; and passing said coated cellulosic material under an embossing roll heated to a temperature above the melting point of said wax, the resulting melting of the Wax acting to develop at point of contact with the embossing roll the contrasting color of the said finely divided oil-soluble color by dissolving it in the said molten water-insoluble pigment, said coating being further coated with a water-insoluble wax having a melting point above 140 F. and below 270 F., said wax coating having dissolvedtherein an oil-soluble color; the remaining portion of said surface being coated with a binder having dispersed therein a finely divided water insoluble pigment, a finely divided oil-soluble color and water-insoluble wax galrticll es having a melting point above 140 F. and below 0 References Cited in the file of this patent UNITED STATES PATENTS 1,535,999 Harrington Apr. 28, '1925 1,582,416 .Mason Apr. 27,1926 1,930,853 Kollek et ,aL. Oct. 17,1933 1,956,197 Lines Apr-.24, .1934 2,099,880 Ellis Nov. 23, 1937 2,248,233 Heritage July 8, .1941 2,288,527 vLumphner June 30, 1942 2,306,525 'Cummings. Dec.,29, 1942 237 .862 Green F,. -.MaY .l, 1945 

10. A METHOD OF OBTAINING DUAL COLOR EFFECTS ON CELLULOSIC MATERIALS BY HOT EMBOSSING WHICH COMPRISES APPLYING TO ONE SURFACE OF SAID CELLULOSIC MATERIAL AN EMULSION, THE INTERNAL PHASE OF SAID EMULSION BEING A WATER-INSOLUBLE WAX HAVING A MELTING POINT ABOVE 140* F. AND BELOW 270* F., THE EXTERNAL PHASE OF SAID EMULSION BEING AN AQUEOUS DISPERSION OF A FINELY DIVIDED WATER INSOLUBLE PIGMENT AND A FINELY DIVIDED OIL-SOLUBLE COLOR IN AN AQUEOUS SOLUTION OF A WATER-SOLUBLE BINDER; DRYING SAID COATING AT A TEMPERATURE SUBSTANTIALLY BELOW THE MELTING POINT OF SAID WAX; AND PASSING SAID COATED CELLULOSIC MATERIAL UNDER AN EMBOSSING ROLL HEATED TO A TEMPERATURE ABOVE THE MELTING POINT OF SAID WAX, THE RESULTING MELTING OF THE WAX ACTING TO DEVELOP AT POINT OF CONTACT WITH THE EMBOSSING ROLL THE CONTRASTING COLOR OF THE SAID FINELY DIVIDED OIL-SOLUBLE COLOR BY DISSOLVING IT IN THE SAID MOLTEN WAX. 